Porting RPM

[77cruiser]

Thinking of trying a RPM from a Vic. jr.. Would it be worth my effort to open it up to about 2 inches in or how far I could go?

[steve cowan]

JIM,
Rpm airgap??
What application

[77cruiser]

JIM,
Rpm airgap??
What application

Regular RPM mild 421 535hp.
Just thought I'd give it a shot might make it to the track, might not.

[6.50camaro]

I did a RPM air gap a few years ago . The port and runners are about the same the regular RPM I believe . The runners taper down quite a bit at the flange so a good deep port match should help. Dan

[77cruiser]

I did a RPM air gap a few years ago . The port and runners are about the same the regular RPM I believe . The runners taper down quite a bit at the flange so a good deep port match should help. Dan

That's what I was thinking, looks like I could get in about 2 1/2 inches or to the turn.

[steve cowan]

I just had a look at my as cast airgap
DAN is correct about taper to the flange, the outside ports go in a couple of inches then the Port becomes trapezoid in shape, measuring the width of the Port you can open at the flange and a couple of inches up the runner about 0.100" I would think as far as the Port height it is very hard to measure in my opinion.
My track testing with my combination I ran last year 383sbc 430-440hp
Airgap with one inch open spacer was quicker in the eighth mile but my Vic jnr was a couple of tenths quicker and 3 mph faster in the quarter.

[RevTheory]

I was wondering about rolling a 3/8ths radius from the plenum into the runners but I have no evidence for or against it.

[steve cowan]

I was wondering about rolling a 3/8ths radius from the plenum into the runners but I have no evidence for or against it.

access into the runners is the problem,its so damn tight.
only way really is to cut the intake down the middle ,port and tig weld back up but for what ??
the manifold of choice for me at the moment is the 300-25

[6.50camaro]

I was wondering about rolling a 3/8ths radius from the plenum into the runners but I have no evidence for or against it.

I also did this , can not say it was a 3/8 radius but I did lay it back the best I could . Dont know if it help or not . I did all the work before running the manifold . Dan

[68corvette]

I was recently rotating RPM manifold on table and could not figure out anything else to do except matching the ports to head.

[77cruiser]

I was recently rotating RPM manifold on table and could not figure out anything else to do except matching the ports to head.

That's more than likely what will happen, it will give me the feel good, feeling Like Steve says no room to do anything unless it gets cut in half.